Pretreatment of biological feedstocks for hydroconversion in fixed-bed reactors

Abstract

A process for pretreating biological feedstocks for hydroconversion in a fixed-bed reactor. A feed stream having free fatty acids, fatty acid esters, or combinations thereof is contacted with a citric acid solution. The biological feedstock is separated from the aqueous solution to efficiently produce a pretreated biological feedstock substantially absent of metals and phosphorus.

1 . A process for pre-treating biological feedstocks for hydroconversion comprising the steps of:
 (a) providing a biological feedstock stream containing free fatty acids, fatty acid esters, or combinations thereof;   (b) contacting the biological feedstock stream with an aqueous acid solution; and   (c) separating an aqueous phase to yield a pre-treated biological feedstock having an ash content less than about 100 wppm.   
   
   
       2 . The process of  claim 1  wherein the biological feedstock comprises animal fat and yellow grease. 
   
   
       3 . The process of  claim 1  further comprising the step of:
 filtering the biological feed stock stream.   
   
   
       4 . The process of  claim 1  wherein the acid is citric acid. 
   
   
       5 . The process of  claim 4  wherein the concentration of the citric acid solution is at least 0.5 wt. %. 
   
   
       6 . The process of  claim 1  wherein the acid is sulfuric acid, phosphoric acid, hydrochloric acid, nitric acid, acetic acid, or carbonic acid. 
   
   
       7 . The process of  claim 1  further comprising the step of:
 feeding the pre-treated biological feedstock to a hydroconversion unit.   
   
   
       8 . The process of  claim 7  wherein the hydroconversion unit includes a fixed-bed reactor. 
   
   
       9 . The process of  claim 8  wherein the fixed-bed reactor converts pre-treated biological feedstock to hydrocarbons. 
   
   
       10 . The process of  claim 1  wherein the ash content of the biological feedstock is reduced by at least 90%. 
   
   
       11 . The process of  claim 1  wherein the pretreated biological feedstock having an ash content less than about 80 wppm ash. 
   
   
       12 . The process of  claim 1  wherein the pre-treated biological feedstock having an ash content less than about 50 wppm ash. 
   
   
       13 . The process of  claim 1  wherein the total metals and phosphorus of the pretreated biological feedstock is less than about 40 wppm 
   
   
       14 . The process of  claim 13  wherein the metals include calcium, iron, potassium, magnesium, and sodium. 
   
   
       15 . The process of  claim 1  further comprising the steps of:
 providing a plurality of contacting steps; and   providing a plurality of separating steps.